This invention relates to wood preservation.
In WO 96/36615 and 97/00612, are disclosed various cyclic ureas as fungicides for combating plants diseases.
We have now found that a specific group of compounds are very effective in controlling wood damaging fungi and particularly basidiomycete fungi, which cause rot, as well as sapstain fungi which spoil the appearance of the wood.
The invention thus provides the use for combating wood damaging fungi of compounds of formula I 
where R is
a) 
or
b) 
where each R1, which may be the same or different, is C1-4-alkyl, C1-4-alkoxy, trifluoromethyl or halogen and n is 0 to 3.
Examples of fungi that can be controlled using the compounds of formula I include Coriolus versicolor, Poria placenta, Lentinus lepideus, Trametes versicolor, Serpula lacrymans, Coniophora puteana and Gloeophyllum trabeum. 
In general the wood rotting fungi appear as a complex of two or more of these species.
We have also found that the compound of formula I is particularly effective when used in combination with other wood fungicides, such as fluquinconazole, tebuconazole, dichlone, carbendazim, prochloraz, sipconazole and cyproconazole.
The compound of formula I can be applied in a suitable, usually liquid formulation usually containing surfactants and other conventional additives and usually after dilution with water. The concentration may vary over a wide range, e.g. from 0.001 to 10%, preferably from 0.1 to 1%, by weight.
The invention is illustrated In the following examples.